The Mercè festival, which takes place in September, is Barcelona's biggest festival.
Barcelonians are crazy people :) They dress up as devils and go around with fireworks in the streets, spraying it all over the innocent bystanders.
It was actually great fun. I first kept my distance a bit but couldn't get any good shots. I was only dressed in jeans and a t-shirt while most of the people standing close were wearing some kind of protection like jackets with hoodies or scarfs around their head. At some stage I just braved it and went on the street, right in the middle of it. The camera protected my face more or less while the UV filter protected the lens. I felt burning on my shoulders a few times and after the event I found out that I had burn holes in my t-shirt. Ah well, it was worth it.
There was also a fireworks display on the hill Montjuïc which was absolutely beautiful and lasted for a long time. There are also a few shots of that display in this slideshow. Just click on one of the photos to go to the set on my flickr page and see the bigger photos.